New thinking on cataract surgery and induced astigmatism

Accurate analysis of surgically induced astigmatism (SIA) in cataract patients requires consensus on the parameters to be considered and how measurements are made and interpreted.

In a guest editorial in the October 2018 issue of the Journal of Cataract and Refractive Surgeons, a distinguished group of ophthalmic surgeons propose a new, more precise and descriptive terminology to better define the source of the induced astigmatism, whether it’s a misaligned toric IOL, IOL tilt, or changes induced by corneal incisions. The authors also recommend that, rather than using fixed-ratio toric IOL calculators that calculate a toric IOL’s corrective effect at the spectacle plane, cataract surgeons should use vergence toric IOL calculators that calculate the toric implant’s corrective effect, based on the spherical power of the IOL and the predicted effective lens position (ELP). They also caution that until validated methods for measuring the posterior cornea become available, anterior corneal changes will most often remain a proxy for total induced corneal astigmatism.